Quantifying performance of high-density mapping catheters in in-vivo and benchtop models

Background/Introduction

High-density mapping catheters enhance the speed and accuracy of 3-dimensional data collection. However, differences in data acquisition, efficiency, and system processing are not well quantified, even for catheters with similar form factors.

Purpose

Compare in-vivo and bench performance of the HD Grid X (EnSite X v 5.0.1) and Optrell (Carto v 8.1.1) catheters. Criteria include mapping and modeling efficiency, electrogram (EGM) amplitude dependence on orientation, and resolution of low voltage boundaries.

Methods

In-vivo: In 6 swine, 5 physicians used each catheter in a randomized order to create models of equivalent detail of the left atrium (LA) and ventricle (LV) during atrial pacing. Comparable mapping parameters were selected between the respective mapping systems. Each mapping catheter was then placed in a stable location at 3 different anatomical sites in the LA and rotated while collecting manual map points. In the right atrium (RA), an independent operator placed groups of 5-6 radiofrequency (RF) lesions with a focal ablation catheter. Each physician, being blinded to the ablated areas, remapped the RA and identified the area(s) they assessed as being ablated. The indicated regions were measured on the mapping system and compared to the actual ablated area(s) observed during necropsy.

Bench: Using a wavefront emulator platform, 2 propagation patterns were created—case 1: a single uniform wavefront propagating across the platform, and case 2: two uniform wavefronts colliding in the center of the platform creating a low-voltage region. For both cases, during map collection, the catheter was oriented at 3 different angles (0, 45, and 90 deg.) relative to the propagation direction. For case 1, the EGM amplitudes were compared. For case 2, the spatial resolution of the low-voltage region was defined by the full-width at half max (FWHM), i.e., the measured width of the area containing less than half the max amplitude.

Results

In-Vivo: Median rate of mapping point acquisition for Grid X was higher than Optrell by 167% (p=0.02; 48,18 points/s) in the LA and 39% (p=0.03; 18,13 points/s) in the LV. Median time for model completion for Grid X was shorter than Optrell by 39% (p=0.047; 318s, 525s) in the LA and 45% (p=0.02; 342s, 620s) in the LV. Grid X measured higher amplitude EGMs in all 3 LA locations (Fig 1). The mean error in the lesion areas identified by Grid X was 25% lower than Optrell (p=0.04; 154, 204 mm²).

Bench: In case 1, Grid X recorded a median normalized amplitude which was 58% larger than Optrell (Fig 1). In case 2, Grid X recorded a median voltage resolution which was 34% finer than Optrell (Fig 2).

Conclusion

Design considerations beyond catheter shape may impact mapping quality and speed. Grid X collects mapping and geometry data faster, is less reliant on catheter orientation to collect high voltage EGMs, and more accurately defines low voltage boundaries compared to Optrell.Figure 1:EGM Amplitude DataFigure 2:Voltage Resolution